JP2001158893A - Method and apparatus for producing synthetic natural gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus therefor capable of efficiently mass-producing a clean synthetic natural gas from inexpensive water and carbon as feedstocks. SOLUTION: This apparatus has such a scheme that a cathode assembly 48 and a tubular anode 26 are set up inside housings 14, 16, 18 to provide an arc reaction chamber 76 having 1st and 2nd reaction zones Z1, Z2, the anode 26 and a cathode holder 22 are cooled by cooling passage means 38 and 40 each communicating with an inlet 32, steam generated in a steam generation unit 50 is injected via an injector ring 24 into the 1st reaction zone Z1 and subjected to catalytic reaction with the arc to form a hydrogen-rich gas, which, in turn, is subjected to catalytic reaction with the carbon of a carbonaceous material 79 in the 2nd reaction zone Z2 to obtain the objective methane-rich gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternative natural gas production method, and more particularly to a synthetic natural gas production method and apparatus.

[0002]

BACKGROUND ART As an effective measure against depletion of petroleum resources, air pollution due to exhaust gas from factories and automobiles, and global warming due to carbon dioxide emission, in recent years, it has been used as a fuel for transportation equipment such as automobiles and ships, or for power generation Natural gas has attracted attention as a fuel. In addition, natural gas is widely used for city gas year by year. In particular, a method for producing alternative natural gas has been proposed as a measure against peak loads.

[0003] US Pat. No. 4,092,129 discloses that a porous electrode is arranged in an electrolytic cell and H ₂ and O ₂ are electrolyzed.
And reacting O ₂ with the coal powder to produce CO;
On the other hand, a synthetic natural gas production method and an apparatus for producing methane by reacting CO and H ₂ in a reaction chamber have been proposed. This method not only increases the size of the apparatus due to low methane production efficiency, but also requires an additional purification step because the sulfuric acid in the coal is mixed into the produced gas.

[0004]

SUMMARY OF THE INVENTION The above-mentioned synthetic natural gas producing apparatus is inefficient, and it has not been possible to mass-produce synthetic gas at low cost on a commercial or industrial scale. Moreover, since a large amount of sulfuric acid is contained in the produced gas because coal powder is used as a raw material, clean synthetic natural gas cannot be provided.

It is an object of the present invention to provide a method and apparatus for producing clean synthetic natural gas at low cost.

Another object of the present invention is to provide a method for producing synthetic natural gas and an apparatus therefor which enable mass production of low-cost, clean synthetic natural gas on a commercial or industrial scale using inexpensive water as a raw material. With the goal.

[0007]

Means for Solving the Problems In the first invention of the present application, a synthetic natural gas producing apparatus has a housing means having an inlet for water introduction and an outlet for discharging methane-rich gas, a first electrode means supported in the housing means, A second electrode means spaced from the first electrode means; an arc reaction chamber having first and second reaction zones formed between the first and second electrode means; Power supply means for supplying power to the particulate hydrogen generating means and particulate carbon-containing material charged in the zone and the first and second electrode means to generate an arc in the arc reaction chamber; and connecting the inlet and the arc reaction chamber to the arc. And a passage means for introducing water into the reaction chamber.

In the second invention of the present application, the synthetic natural gas production method includes providing a first reaction zone and a second reaction zone in an arc reaction chamber, and treating water by a plasma arc in the first reaction zone to generate a hydrogen-rich gas. This is then achieved by contacting the hydrogen-rich gas with carbon of the carbon-containing material in a second reaction zone in the presence of a plasma arc to produce a methane-rich gas.

[0009]

In the method and apparatus for producing synthetic natural gas of the present invention, a first reaction zone and a second reaction zone are provided in an arc reaction chamber, and water is thermally decomposed by a plasma arc in the first reaction zone to generate a hydrogen-rich gas. Then, in the second reaction zone in the presence of a plasma arc, hydrogen is brought into contact with carbon of the carbon-containing material to obtain a methane-rich gas.

[0010]

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. 1 and 2, the synthetic natural gas producing apparatus 10 includes a front cover 12, a front housing 14, a center housing 16 and a rear housing 18. Housings 14, 16, 18
Are made of ceramic and other heat-resistant insulating materials, respectively.
It has a common central shaft 20 and is connected by screws (not shown). For example, in FIG. 2, the screw passes through the through hole 21 of the center housing 16 and is screwed into a tap hole of the rear housing 18. In FIG. 2, a cathode holder 22, an injector ring 24 and an anode 26 are housed inside the housings 18, 16, and 14. The cathode holder 22 includes housings 18 and 16.
It is fixedly supported inside. Injector ring 24
Is fixedly supported inside the center housing 16 in a state sandwiched between the cathode holder 22 and the anode 26. The rear portion of the anode 26 extends partially into the center housing 16 and is held in a fixed position by the front cover 12.

The cathode holder 22 and the anode 26 are connected to an AC power source, a DC power source, or a high-frequency pulse power source (not shown) for generating a plasma arc via terminal members 28 and 30, respectively. Terminal member 28 is screwed to cathode holder 22, and terminal member 30 is tapped hole 14 a of front housing 14 so as to conduct with anode 26.
Screw. The housing 14 and the front cover 12 each include a water inlet 32 and a product gas outlet 34. Water is supplied to the inlet 32 via a water supply pipe 36 as a raw material. Inside the housings 14 and 16, there are provided first cooling passage means 38 for cooling the outer periphery of the anode 26, second cooling passage means 40 for cooling the cathode holder 22, and an intermediate passage 41.

In FIG. 2, the cathode holder 22 includes a front end 46 for holding a screw portion 44 of the cathode assemble 42. The cathode assembly 42 is the anode 2
6 is provided with a rod-shaped cathode 48 extending inside. Cathode 48
Is made of an electrode material such as thorium-containing tungsten or hafnium nitride. The central portion of the cathode holder 22 is located at the steam generator 5 disposed in the second cooling means 40.
0 is provided. The steam generating section 50 has a central hole 52 in the cathode holder 22, a tubular copper mesh 54, and a copper mesh 5.
A plurality of pellets or ball-shaped solid heat transfer bodies 56 filled in 4 and dissipating heat of the cathode assemblage 48 to generate steam from the preheated water are provided. The second cooling passage means 40 includes an annular passage 58, an inlet 60, and an outlet 62 formed in the cathode holder 22. The annular passage 58 communicates with the first cooling passage means 38. A steam supply passage 64 is arranged between the outlet 62 and the injector ring 24. The steam supply passage 64 is formed in the rear housing 18, and a flow regulating valve 66 for adjusting the steam supply amount is disposed at an intermediate portion thereof. The center housing 16 has a passage 68 for supplying steam to the injector ring 24. An annular passage 70 is formed between the outer periphery of the injector ring 24 and the inner wall of the center housing 16. The injector ring 24 includes a plurality of steam injection nozzles 72 for injecting steam in a tangential direction,
A vortex chamber 74 is formed between the inner wall and the outer periphery of the cathode assemble 42.

An arc reaction chamber 76 including first and second reaction zones Z 1 and Z 2 is formed between the cathode assembly 42 and the inner wall of the anode 26. First reaction zone Z1
A granular hydrogen generating means 78 made of a number of high melting point materials.
Is filled. As a first example, the granular hydrogen generating means 78 is formed of a ball-shaped electrode body having a diameter of 2 to 30 mm, and may be formed of the same material as the cathode 48. As a second example, the granular hydrogen generating means 78 is composed of a mixture of a granular conductor and a granular non-conductor made of a ball-shaped electrode material, and the mixture ratio is 1: 1.5 to 1. It is determined in the range of 5: 1. The granular non-conductor may be selected from silicon dioxide or ceramic made of ore such as silica or quartz. In this case, silicon dioxide is effective not only as an insulating material but also for decomposing water into synthetic natural gas oxygen while repeating oxidation and reduction in the presence of an arc. As a third example, the particulate hydrogen generating means 78 is a device for generating particulate titanium oxide (T ₁ O).
₂ ) A catalyst selected from the group consisting of a catalyst, an iron oxide (Fe ₃ O ₄ ) catalyst, and a silicon oxide (SiO ₂ ) catalyst. The purpose of the granules 78 is to uniformly generate a small plasma arc due to sparks in a number of gaps of the granules in the arc reaction chamber 76. Therefore, a very large amount of a small plasma arc is generated in the first reaction zone Z1 in the arc reaction chamber 76, and the efficiency of the contact reaction with steam is remarkably improved, and the efficiency of water decomposition is increased. When electrons are emitted from the cathode 48, the particulate catalyst causes FeO, Fe
₃ O ₄ , SiO, SiO ₂ ; reduced from metal oxides such as TiO and TiO _{2 to} metals such as Fe, FeO; Si, SiO; Ti and TiO, and extremely reactive oxygen atoms (excited state oxygen) Atom) O ^* is generated. It is considered that the oxygen atom O ^* contributes to oxidizing the steam H ₂ O and decomposing it to H ₂ + O ₂ . As described above, since the catalyst repeats oxidation-reduction in the presence of electrons, the water splitting reaction continues, and cracked gas is continuously generated from steam. In order to obtain a cracked gas containing only synthetic natural gas, the granular material 78 is filled with a catalyst ball made of iron oxide such as magnetite (Fe ₃ O ₄ ) in the first reaction zone Z1, and then the power is supplied to the electrode. It is advisable to start the actual operation after generating oxygen deficient magnetite through synthetic natural gas while generating a plasma arc. In this case, a plurality of synthetic natural gas producing apparatuses are connected in parallel, and synthetic natural gas can be continuously obtained from water by periodically introducing synthetic natural gas into the apparatus. In FIG. 2, a granular carbon-containing material 7 for producing methane-rich gas is provided in a second reaction zone Z2.
9 are filled. The particulate carbon-containing material 79 is selected from a bulk, solid, or powder material selected from the group consisting of charcoal, bamboo charcoal, coke, graphite, carbon, and mixtures thereof. Note that the carbon-containing material 79 may be one obtained by depositing carbon on the surface of the catalyst metal. As an example, the catalyst metal may be a simple substance or a nickel-containing magnetite (Fe ₃ O
₄ ) Select from iron oxides such as 300-500 ° C
To activate oxygen-deficient magnetite through hydrogen,
Thereafter, carbon dioxide may be introduced into the magnetite surface by introducing carbon dioxide. In FIG. 2, the carbon-containing material 7
When a carbon ball having a diameter of 2 to 30 mm is used as 9,
As the carbon balls come into point contact with each other, many gaps are formed between the carbon balls. Therefore, when power is supplied to the electrodes, a current flows through each carbon ball, and a plasma arc is generated by sparks. This arc is uniformly generated in most of the gaps of the carbon ball filled in the second reaction zone Z2. Therefore, the hydrogen of the hydrogen-rich gas generated in the first reaction zone Z1 contacts and reacts with the carbon of the carbon ball in the presence of the plasma arc to generate a methane-rich gas. A disk-shaped perforated plate 80 is arranged on the front side of the arc reaction chamber 76. Anode 2
A quenching chamber 82 and a quenching fin 84 are formed at the front end of the cooling chamber 6, and the quenching chamber 82 communicates with the first cooling passage means 38 via a passage 86. A quenching chamber 88 and a quenching fin 90 are formed in the center of the front cover 12. The quenching chambers 82 and 88 and the quenching fins 84 and 90 are axially aligned and continuous. Methane rich gas is perforated plate 8
After squirting from 0 and expanding, it is quenched by the quench fins 88 and 90 and then discharged from the outlet 34.

In the above configuration, water as a raw material is also used as cooling water. For this purpose, cooling water is introduced from the inlet 32 into the first cooling passage means 38,
A part is supplied to the quenching chambers 82 and 88 through the passage 86,
The remainder is supplied to the second cooling passage means 40 via the passage 41. At this time, the anode 26 and the cathode 48 are energized by a DC power supply, an AC power supply or a high-frequency pulse power supply,
Further, a plasma arc is generated in the second reaction zones Z1 and Z2. In this state, the outer periphery of the anode 26 is continuously cooled by the cooling water. The cooling water then flows into the annular passage 58 and the inlet 60 of the second cooling passage means 40 to cool the cathode holder 22 and is preheated to hot water.
This hot water comes into contact with the high-temperature heat transfer body 56 in the steam generating section 50 to generate steam. Steam is a flow control valve 66
The flow rate of the cathode assemble 42 is cooled while flowing into the swirl chamber 74 via the spray nozzle 72, and flows into the first reaction zone Z1. At this time, the steam is converted into a hydrogen-rich gas in the first reaction zone Z1 in the presence of the plasma arc. Hydrogen-rich gas is second
A methane-rich gas is generated in contact with the carbon-containing material 79 in the presence of the plasma arc in the reaction zone Z2. When the hydrogen-rich gas is composed of hydrogen and oxygen as in the following chemical formula (1), the methanation reaction proceeds as in the chemical formula (2), and a mixed gas of methane and carbon dioxide is generated. On the other hand, when the hydrogen-rich gas contains only hydrogen in the first reaction zone Z1, the hydrogen reacts with the carbon in the second reaction zone to produce methane as shown in chemical formula (3).

[0015]

[Formula] 2H ₂ O → 2H ₂ + O ₂ (1) 2H ₂ + O ₂ + 2C → CH ₄ + CO ₂ (2) 2H ₂ + C → CH ₄ (3) After being quenched by the fins 84 and 90, it is discharged from the outlet 34.

FIG. 3 shows a modified example of the synthetic natural gas producing apparatus of FIG. 2, and the same parts as those of FIG. 2 are denoted by the same reference numerals. In FIG. 3, an anode 100 is a multiphase electrode 102, 104, 10 consisting of a tubular three-phase AC electrode concentric with the cathode 48.
6, each of which has an R
Phase, S phase, and T phase. The cathode holder 42 is preferably connected to the neutral point of the three-phase AC power supply 108 or has a ground potential. The arc reaction chamber 76 has first and second reaction zones Z1 and Z2, which are filled with a granular hydrogen generating means 78 and a carbon-containing material 79, respectively. The electrode 106 includes a quenching chamber 110. An insulating spacer 112 is disposed between the electrodes 102 and 104.
4 are arranged between the electrodes 104, 106. Polyphase electrode 10
When the three-phase AC voltage is supplied to 2, 104 and 106, a minute arc is generated in the gap of the granular material 78 between the multi-phase electrodes 102 and 104 and the neutral electrode 48 at the first timing. Next, at the second timing, the multiphase electrode 1
A potential difference is generated between the neutral electrodes,, and the neutral electrode, and a minute arc is generated in a gap between the granular materials, between them. At the third timing, the multi-phase electrode 1
02, 106 and the neutral electrode 48 generate a potential difference,
An arc is generated in the gap between the granules 78 and 79 between them. At the fourth timing, all the multiphase electrodes 10
Granules 7 between 2, 104, 106 and neutral electrode 48
An arc is generated between the gaps 8 and 79. At the fifth timing, an arc is generated in the gap between the granules 78 and 79 between the multiphase electrodes 104 and 106 and the neutral electrode 48. At the sixth timing, the multiphase electrodes 102, 104, 10
An arc is created in the gap between the granules 78, 79 between 6 and the neutral electrode. Thereafter, the same cycle is repeated. As described above, in the arc reaction chamber 76, the arc generation position is sequentially changed according to the voltage phase, and the ionized gas at a plurality of arc generation positions is constantly supplied. For this reason, even if the steam amount is increased, the arc is not interrupted in the arc reaction chamber 76 up to the gaps of the granules 78 and 79, and the first reaction zone Z
At 1, stable hydrogen-rich gas is generated from steam,
A methane-rich gas is generated in the second reaction zone Z2.
The three-phase AC power supply 108 may be constituted by a high-frequency AC power supply.

FIG. 4 shows another modification of the synthetic natural gas production apparatus of FIG. 2, and the same parts as those of FIG. 2 are denoted by the same reference numerals. In FIG. 4, the first electrode is a front housing 1.
4 (see FIG. 2), a flat cathode 122 supported by the cathode holder 42, and an anode 120
And the cathode 122 and the front housing 1
4 and an insulating sleeve 124 housed in the center housing 16. The anode 120 is connected to the cooling water passage 12.
6, a quenching chamber 128, a quenching fin 130, and a methane-rich gas injection port 132. The cathode 122 has a steam supply port 134 and communicates with the swirl chamber 74 of the injector ring 24. An arc reaction chamber 76 including first and second reaction zones Z1 and Z2 is formed inside the insulating sleeve 124, and granular hydrogen generating means 78 and a particulate carbon-containing material 79 are provided in the first and second reaction zones Z1 and Z2. Is filled. When AC power, DC power or high-frequency pulse power is supplied to the anode 120 and the cathode 122, a plasma arc is generated in the gap between the granular hydrogen generating means 78 and the granular carbon-containing material 79. Steam flows from the vortex chamber 74 to the cathode 1
22 through the steam supply port 134 of the first reaction zone Z.
Once introduced into the steam, the steam is thermally decomposed by the plasma arc to produce a hydrogen-rich gas. The hydrogen-rich gas contacts and reacts with the carbon of the carbon-containing material in the second reaction zone Z2 to generate a methane-rich gas. The methane-rich gas is quenched by the quench fins 130 while ejecting from the ejection port 132, and is discharged from the outlet 136. In FIG. 4, a second plate-like electrode having a through hole is disposed between the anode 120 and the cathode 122, and these electrodes are connected to a three-phase AC power supply or a high-frequency AC power supply as in the embodiment of FIG. Is also good.

In the embodiment of FIG. 3, the neutral electrode 48 may be omitted. Further, the three-phase AC electrode may be a four-phase AC four electrode or a six-phase AC six electrode.

[0019]

As is clear from the above, according to the synthetic natural gas production method and the apparatus of the present invention, low-cost water, distilled water, pure water, drinking water, industrial water or seawater is used as a raw material. It enables mass production of clean synthetic natural gas, and greatly contributes as a new energy source or as a raw material for the chemical industry.

[Brief description of the drawings]

FIG. 1 is an external view of a synthetic natural gas production apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view of the synthetic natural gas production apparatus of FIG.

FIG. 3 is a modified example of the synthetic natural gas production apparatus of FIG.

FIG. 4 is another modified example of the synthetic natural gas production apparatus of FIG.

[Explanation of symbols]

12 front cover, 14 front housing,
16 center housing, 18 rear housing, 20 center axis, 22 cathode holder, 24 injector ring, 26 anode, 28, 30 terminal member, 32 inlet, 34 outlet, 38
1st cooling passage, 40 2nd cooling passage, 42 cathode assemble, 48 cathode, 50 steam generation part,
72 ejection nozzle, 74 vortex chamber, 76 arc reaction chamber, 78 granular hydrogen generation means, 79 granular carbon-containing material, 82, 88 quenching chamber, 102, 104, 106
Tubular three-phase AC electrode, 108 three-phase AC power supply, 110
Quenching chamber, 122 flat cathode, 126 anode, Z1
First reaction zone, Z2 Second reaction zone

Claims (18)

[Claims] 1. A housing means having an inlet for water introduction and an outlet for discharging methane-rich gas, a first electrode means supported in the housing means, and a second electrode means spaced from the first electrode means. And the first
An arc reaction chamber having first and second reaction zones formed between the first and second electrode means, and a particulate hydrogen generating means and a particulate carbon-containing material filled in the first and second reaction zones, respectively, An apparatus for producing synthetic natural gas, comprising: power supply means for supplying power to the second electrode means to generate an arc in the arc reaction chamber; and passage means for connecting the inlet and the arc reaction chamber to introduce water into the arc reaction chamber. 2. The synthetic natural gas producing apparatus according to claim 1, wherein the passage means includes a cooling means. 3. The synthetic natural gas producing apparatus according to claim 1, further comprising an electrode holder housed in the housing means and supporting the second electrode means. 4. The synthetic natural gas production apparatus according to claim 3, further comprising steam generating means, wherein the steam generating means is connected to the passage means. 5. The synthetic natural gas production apparatus according to claim 4, further comprising an injector means for supplying steam to the arc reaction chamber. 6. The synthetic natural gas production apparatus according to claim 1, wherein the granular hydrogen generating means is selected from the group consisting of at least one of a granular electrode body and a granular catalyst. 7. The particulate hydrogen generating means according to claim 1, wherein the particulate hydrogen generating means comprises a mixture of a particulate electrode body, a particulate conductor, and a particulate nonconductor, and the mixing ratio is in the range of 1: 1.5 to 1.5: 1. Synthetic natural gas production equipment. 8. The synthetic natural gas production apparatus according to claim 3, wherein the first electrode means comprises a tubular anode, and the second electrode means comprises a cathode assemble supported by an electrode holder and concentric with the tubular anode. 9. The synthetic natural gas production system according to claim 1, wherein the first and second electrode means comprise three-phase AC electrodes spaced apart in the axial direction, and the power supply means comprises a three-phase AC power supply. apparatus. 10. The synthetic natural gas production apparatus according to claim 9, further comprising a neutral electrode, wherein the neutral electrode is grounded. 11. The synthetic natural material according to claim 3, wherein the first electrode means comprises an anode, and the second electrode means comprises a flat cathode supported by an electrode holder and spaced axially from the anode. Gas production equipment. 12. The synthetic natural gas production apparatus according to claim 7, wherein the particulate catalyst comprises a solid catalyst selected from the group consisting of a titanium oxide-based catalyst, an iron oxide-based catalyst, and a silicon oxide-based catalyst. 13. The synthetic natural gas producing apparatus according to claim 7, wherein the particulate non-conductor is a silicon oxide-based catalyst. 14. The method according to claim 1, further comprising:
An apparatus for producing synthetic natural gas, comprising: a front cover fixed to a housing means; and a quenching means in which the front cover is disposed at an outlet. 15. The method according to claim 4, further comprising:
An apparatus for producing synthetic natural gas comprising a flow rate adjusting means between a steam generating means and an injector means. 16. A first reaction zone and a second reaction zone are provided in an arc reaction chamber, and water is treated by a plasma arc in the first reaction zone to generate a hydrogen-rich gas, and then the hydrogen-rich gas is added to the presence of the plasma arc. A method for producing synthetic natural gas, comprising: producing a methane-rich gas by contacting and reacting with carbon of a carbon-containing material in a second reaction zone. 17. The synthetic natural gas production according to claim 16, wherein the first reaction zone is filled with the particulate electrode bodies, a plasma arc is generated in these gaps, and water or steam passes through the gaps in the granular electrode bodies. Law. 18. The method according to claim 16, wherein the first reaction zone is filled with a mixture of the particulate electrode body and the particulate non-conductor, and the mixture ratio is selected from the range of 1: 1.5 to 1.5: 1. Synthetic natural gas production method.